1. Field of the Invention
The present invention relates to an alternator used in an automotive vehicle.
2. Description of Related Art
In a conventional alternator, a cooling fan connected to a rotor shaft generates airflows in an axial direction for cooling a field winding and in a radial direction for cooling coil ends of an armature winding. In some alternators, a fan base for rectifying directions of the airflows is disposed between an end of a pole core and the cooling fan. JP-B2-3497896 discloses such an alternator that includes a slip-ring molded together with terminals for electrically connecting a slip-ring to a field winding. In this alternator, a rotor shaft is forcibly inserted into a center hole of the molded slip-ring.
In an alternator having a cooling fan, the cooling fan has to be connected to a rotor shaft coaxially and at a correct position in a rotational direction of the rotor shaft. If the cooling fan is not coaxially connected to the rotor, fan noises will be generated according to rotation of the cooling fan. It is also important to be able to connect the cooling fan and the fan base to the rotor at a right position in a simple process. For connecting a cooling fan coaxially to a rotor shaft in a simple process, JP-Y2-5-8781 proposes an alternator, in which a fan base is mechanically connected to a cooling fan and a fringe of a center hole of the cooling is engaged with the rotor shaft.
In the alternator proposed by JP-Y2-5-8781, however, the cooling fan may not be correctly positioned in the rotational direction though it can be coaxially connected to the rotor shaft. If the cooling fan is not correctly positioned in the rotational direction relative to the fan base or the pole core, welding between the cooling fan and the fan base may not be successfully performed. Therefore, it has been required to use an additional jig for correctly positioning the cooling fan in the rotational direction.